Golf Balls having Two or More Core Layers Formed from HNP Compositions

ABSTRACT

The present invention is directed to golf balls having a layer formed from a relatively soft HNP composition and a layer formed from a relatively hard HNP composition. Golf balls of the present invention have at least three layers, including an inner core layer, an outer core layer, a cover, and optionally an intermediate core layer. The present invention is not limited by which golf ball layers are formed from an HNP composition, so long as at least one layer is formed from a relatively soft HNP composition and at least one layer is formed from a relatively hard HNP composition. Relatively soft HNP compositions of the present invention comprise a highly neutralized acid copolymer preferably having a modulus of from 1,000 psi to 50,000 psi. Relatively hard HNP compositions of the present invention comprise a highly neutralized acid copolymer preferably having a modulus of from 25,000 psi to 150,000 psi.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/304,962, filed Dec. 15, 2005, which is acontinuation-in-part of U.S. patent application Ser. No. 10/797,810,filed Mar. 10, 2004, now U.S. Pat. No. 6,988,962, and U.S. patentapplication Ser. No. 10/797,699, filed Mar. 10, 2004, now U.S. Pat. No.6,981,926, the entire disclosures of which are hereby incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention is directed to golf balls comprising a layerformed from a relatively soft HNP composition and a layer formed from arelatively hard HNP composition. The present invention is not limited bywhich layer is formed from the soft HNP composition and which layer isformed from the hard HNP composition, so long as both layers are presentin the golf ball.

BACKGROUND OF THE INVENTION

Conventional golf balls can be divided into two general classes: solidand wound. Solid golf balls include one-piece, two-piece (i.e., singlelayer core and single layer cover), and multi-layer (i.e., solid core ofone or more layers and/or a cover of one or more layers) golf balls.Wound golf balls typically include a solid, hollow, or fluid-filledcenter, surrounded by a tensioned elastomeric material, and a cover.

Golf ball core and cover layers are typically constructed with polymercompositions including, for example, polybutadiene rubber,polyurethanes, polyamides, ionomers, and blends thereof. Ionomers,particularly ethylene-based ionomers, are a preferred group of polymersfor golf ball layers because of their toughness, durability, and widerange of hardness values.

Golf ball compositions comprising highly neutralized acid polymers areknown. For example, U.S. Patent Application Publication No.2003/0130434, the entire disclosure of which is hereby incorporatedherein by reference, discloses melt-processible, highly-neutralizedethylene acid copolymers and process for making them by incorporating analiphatic, mono-functional organic acid in the acid copolymer and thenneutralizing greater than 90% of all the acid groups present. The use ofsuch compositions in various golf ball layers is disclosed. Also, U.S.Patent Application Publication No. 2005/0148725, the entire disclosureof which is hereby incorporated herein by reference, discloses ahighly-resilient thermoplastic composition comprising (a) an acidcopolymer, (b) a salt of a high molecular weight, monomeric organicacid; (c) a thermoplastic resin; (d) a cation source; and (e)optionally, a filler. The reference also discloses one-piece, two-piece,three-piece, and multi-layered golf balls comprising thehighly-resilient thermoplastic composition.

While various uses for highly neutralized acid polymers in golf ballshave been discovered, there is a need in the industry to broaden theapplicability of highly neutralized acid polymers to particular golfball constructions having desirable spin, feel, and COR properties. Thepresent invention provides such golf ball constructions through the useof a layer formed from a relatively soft HNP composition and a layerformed from a relatively hard HNP composition.

SUMMARY OF THE INVENTION

In one embodiment, the present invention is directed to a golf ballcomprising an inner core layer, an outer core layer, and a cover. Theinner core layer is formed from a first HNP composition and the outercore layer is formed from a second HNP composition. The first HNPcomposition has a Shore D hardness of 55 or less and comprises a highlyneutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymer.The second HNP composition has a Shore D hardness of 45 or greater andcomprises a highly neutralized ethylene/(meth)acrylic acid copolymer.The Shore D hardness of the first HNP composition is less than the ShoreD hardness of the second HNP composition.

In another embodiment, the present invention is directed to a golf ballcomprising an inner core layer, an outer core layer, and a cover. Theinner core layer is formed from a first HNP composition and the outercore layer is formed from a second HNP composition. The first HNPcomposition has a Shore D hardness of 45 or greater and comprises ahighly neutralized ethylene/(meth)acrylic acid copolymer. The second HNPcomposition has a Shore D hardness of 55 or less and comprises a highlyneutralized ethylene/(meth)acrylic acid/alkyl (meth)acrylate copolymer.The Shore D hardness of the first HNP composition is greater than theShore D hardness of the second HNP composition.

In another embodiment, the present invention is directed to a golf ballcomprising an inner core layer, an outer core layer, an intermediatecore layer disposed between the inner core layer and the outer corelayer, and a cover. The inner core layer comprises a diene rubbercomposition, the outer core layer is formed from a first HNPcomposition, and the intermediate core layer is formed from a second HNPcomposition. The first HNP composition has a Shore D hardness of 45 orgreater and comprises a highly neutralized ethylene/(meth)acrylic acidcopolymer. The second HNP composition has a Shore D hardness of 55 orless and comprises a highly neutralized ethylene/(meth)acrylicacid/alkyl (meth)acrylate copolymer. The Shore D hardness of the firstHNP composition is greater than the Shore D hardness of the second HNPcomposition.

In yet another embodiment, the present invention is directed to a golfball comprising an inner core layer, an outer core layer, anintermediate core layer disposed between the inner core layer and theouter core layer, and a cover. The inner core layer comprises a dienerubber composition, the outer core layer is formed from a first HNPcomposition, and the intermediate core layer is formed from a second HNPcomposition. The first HNP composition has a Shore D hardness of 55 orless and comprises a highly neutralized ethylene/(meth)acrylicacid/alkyl (meth)acrylate copolymer. The second HNP composition has aShore D hardness of 45 or greater and comprises a highly neutralizedethylene/(meth)acrylic acid copolymer. The Shore D hardness of the firstHNP composition is less than the Shore D hardness of the second HNPcomposition.

DETAILED DESCRIPTION OF THE INVENTION

Golf balls of the present invention have at least two layers formed fromhighly neutralized acid polymer (“HNP”) compositions. More particularly,golf balls of the present invention have at least one layer formed froma relatively soft HNP composition, and at least one layer formed from arelatively hard HNP composition.

As used herein, “highly neutralized acid polymer” refers to an acidpolymer after at least 80%, preferably at least 90%, more preferably atleast 95%, and even more preferably 100%, of the acid groups of the acidpolymer are neutralized.

As used herein, “hardness” refers to Shore D hardness as measuredaccording to ASTM D2240.

As used herein, “modulus” refers to flexural modulus as measured using astandard flex bar according to ASTM D790-B.

Relatively Soft HNP Composition

Relatively soft HNP compositions of the present invention have a Shore Dhardness of 55 or less, and preferably have a Shore D hardness withinthe range having a lower limit of 10 or 20 or 30 and an upper limit of48 or 50 or 55.

Relatively soft HNP compositions of the present invention comprise atleast one highly neutralized acid polymer. In a preferred embodiment,the highly neutralized acid polymer of the relatively soft HNPcomposition is a low modulus HNP having a modulus within the rangehaving a lower limit of 1,000 or 5,000 or 10,000 psi and an upper limitof 17,000 or 25,000 or 28,000 or 30,000 or 35,000 or 45,000 or 50,000 or55,000 psi. In a particular aspect of this embodiment, the modulus ofthe low modulus HNP is at least 10% less, or at least 20% less, or atleast 25% less, or at least 30% less, or at least 35% less, than that ofthe high modulus HNP discussed below.

HNPs of the relatively soft HNP compositions of the present inventionare salts of acid copolymers. It is understood that the HNP may be ablend of two or more HNPs. The acid copolymer of the HNP is anO/X/Y-type copolymer, wherein O is an α-olefin, X is a C₃-C₈α,β-ethylenically unsaturated carboxylic acid, and Y is a softeningmonomer. O is preferably ethylene. X is preferably selected from (meth)acrylic acid, ethacrylic acid, maleic acid, crotonic acid, fumaric acid,and itaconic acid. (Meth)acrylic acid is particularly preferred. As usedherein, “(meth)acrylic acid” means methacrylic acid and/or acrylic acid.Likewise, “(meth) acrylate” means methacrylate and/or acrylate. Y ispreferably an alkyl(meth)acrylate, wherein the alkyl groups have from 1to 8 carbon atoms. Preferred O/X/Y-type copolymers are those wherein Ois ethylene, X is (meth)acrylic acid, and Y is selected from (meth)acrylate, n-butyl(meth) acrylate, isobutyl(meth)acrylate,methyl(meth)acrylate, and ethyl(meth)acrylate. Particularly preferredO/X/Y-type copolymers are ethylene/(meth) acrylic acid/n-butyl acrylate,ethylene/(meth) acrylic acid/methyl acrylate, and ethylene/(meth)acrylicacid/ethyl acrylate.

The acid copolymer of the HNP typically includes the α-olefin in anamount of at least 15 wt %, or at least 25 wt %, or at least 40 wt %, orat least 60 wt %, based on the total weight of the acid copolymer. Theamount of C₃-C₈ α,β-ethylenically unsaturated carboxylic acid in theacid copolymer is typically within the range having a lower limit of 1or 4 or 6 or 8 or 10 or 15 wt % and an upper limit of 20 or 35 or 40 wt%, based on the total weight of the acid copolymer. The amount ofsoftening monomer in the acid copolymer is typically within the rangehaving a lower limit of 1 or 3 or 5 or 11 or 15 or 20 wt % and an upperlimit of 23 or 25 or 30 or 35 or 50 wt %, based on the total weight ofthe acid copolymer.

Particularly suitable acid copolymers of the HNP of the relatively softHNP composition include very low modulus ionomer-(“VLMI-”) typeethylene-acid polymers, such as Surlyn® 6320, Surlyn® 8120, Surlyn®8320, and Surlyne 9320. Surlyne ionomers are commercially available fromE. I. du Pont de Nemours and Company. Also suitable are DuPont® HPF 1000and DuPont® HPF 2000, ionomeric materials commercially available from E.I. du Pont de Nemours and Company.

Additional suitable acid copolymers are disclosed, for example, in U.S.Patent Application Publication Nos. 2005/0148725, 2005/0020741,2004/0220343, and 2003/0130434, and U.S. Pat. Nos. 5,691,418, 6,562,906,6,653,382, 6,777,472, 6,762,246, and 6,815,480, the entire disclosuresof which are hereby incorporated herein by reference.

In a preferred embodiment, the HNP of the relatively soft HNPcomposition is formed by reacting an acid copolymer, which is optionallypartially neutralized, with a sufficient amount of cation source, in thepresence of a high molecular weight organic acid or salt thereof, suchthat at least 80%, preferably at least 90%, more preferably at least95%, and even more preferably 100%, of all acid groups present areneutralized. The acid copolymer can be reacted with the high molecularweight organic acid or salt thereof and the cation sourcesimultaneously, or the acid copolymer can be reacted with the highmolecular weight organic acid prior to the addition of the cationsource.

Suitable high molecular weight organic acids are aliphatic organicacids, aromatic organic acids, saturated monofunctional organic acids,unsaturated monofunctional organic acids, multi-unsaturatedmonofunctional organic acids, and dimerized derivatives thereof.Particular examples of suitable organic acids include, but are notlimited to, caproic acid, caprylic acid, capric acid, lauric acid,stearic acid, behenic acid, erucic acid, oleic acid, linoleic acid,myristic acid, benzoic acid, palmitic acid, phenylacetic acid,naphthalenoic acid, dimerized derivatives thereof, and combinationsthereof. Salts of high molecular weight organic acids comprise thesalts, particularly the barium, lithium, sodium, zinc, bismuth,chromium, cobalt, copper, potassium, stontium, titanium, tungsten,magnesium, and calcium salts, of aliphatic organic acids, aromaticorganic acids, saturated monofunctional organic acids, unsaturatedmonofunctional organic acids, multi-unsaturated monofunctional organicacids, dimerized derivatives thereof, and combinations thereof. Suitableorganic acids and salts thereof are more fully described, for example,in U.S. Pat. No. 6,756,436, the entire disclosure of which is herebyincorporated herein by reference.

Suitable cation sources include metal ions and compounds of alkalimetals, alkaline earth metals, and transition metals; metal ions andcompounds of rare earth elements; silicone, silane, and silicatederivatives and complex ligands; and combinations thereof. Preferredcation sources are metal ions and compounds of magnesium, sodium,potassium, cesium, calcium, barium, manganese, copper, zinc, tin,lithium, and rare earth metals. The acid copolymer may be at leastpartially neutralized prior to contacting the acid copolymer with thecation source to form the HNP. Methods of preparing ionomers are wellknown, and are disclosed, for example, in U.S. Pat. No. 3,264,272, theentire disclosure of which is hereby incorporated herein by reference.The acid copolymer can be a direct copolymer wherein the polymer ispolymerized by adding all monomers simultaneously, as disclosed, forexample, in U.S. Pat. No. 4,351,931, the entire disclosure of which ishereby incorporated herein by reference. Alternatively, the acidcopolymer can be a graft copolymer wherein a monomer is grafted onto anexisting polymer, as disclosed, for example, in U.S. Patent ApplicationPublication No. 2002/0013413, the entire disclosure of which is herebyincorporated herein by reference.

Relatively soft HNP compositions of the present invention optionallycontain one or more melt flow modifiers. The amount of melt flowmodifier in the composition is readily determined such that the meltflow index of the composition is at least 0.1 g/10 min, preferably from0.5 g/10 min to 10.0 g/10 min, and more preferably from 1.0 g/10 min to6.0 g/10 min, as measured using ASTM D-1238, condition E, at 190° C.,using a 2160 gram weight.

Suitable melt flow modifiers include, but are not limited to, highmolecular weight organic acids and salts thereof, polyamides,polyesters, polyacrylates, polyurethanes, polyethers, polyureas,polyhydric alcohols, and combinations thereof. Suitable organic acidsare aliphatic organic acids, aromatic organic acids, saturatedmono-functional organic acids, unsaturated monofunctional organic acids,multi-unsaturated mono-functional organic acids, and dimerizedderivatives thereof. Particular examples of suitable organic acidsinclude, but are not limited to, caproic acid, caprylic acid, capricacid, lauric acid, stearic acid, behenic acid, erucic acid, oleic acid,linoleic acid, myristic acid, benzoic acid, palmitic acid, phenylaceticacid, naphthalenoic acid, dimerized derivatives thereof. Suitableorganic acids are more fully described, for example, in U.S. Pat. No.6,756,436, the entire disclosure of which is hereby incorporated hereinby reference.

Additional melt flow modifiers suitable for use in compositions of thepresent invention, include the non-fatty acid melt flow modifiersdescribed in copending U.S. patent application Ser. Nos. 11/216,725 and11/216,726, the entire disclosures of which are hereby incorporatedherein by reference.

Relatively soft HNP compositions of the present invention optionallyinclude additive(s) and/or filler(s) in an amount of 50 wt % or less, or30 wt % or less, or 15 wt % or less, based on the total weight of therelatively soft HNP composition. Suitable additives and fillers include,but are not limited to, chemical blowing and foaming agents, opticalbrighteners, coloring agents, fluorescent agents, whitening agents, UVabsorbers, light stabilizers, defoaming agents, processing aids, mica,talc, nano-fillers, antioxidants, stabilizers, softening agents,fragrance components, plasticizers, impact modifiers, TiO₂, acidcopolymer wax, surfactants, and fillers, such as zinc oxide, tin oxide,barium sulfate, zinc sulfate, calcium oxide, calcium carbonate, zinccarbonate, barium carbonate, clay, tungsten, tungsten carbide, silica,lead silicate, regrind (recycled material), and mixtures thereof.Suitable additives are more fully described in, for example, U.S. PatentApplication Publication No. 2003/0225197, the entire disclosure of whichis hereby incorporated herein by reference.

Relatively soft HNP compositions of the present invention optionallycontain a high modulus HNP.

In a particular embodiment, the relatively soft HNP composition has amoisture vapor transmission rate of 8 g-mil/1000 in²/day or less (i.e.,3.2 g-mm/m²·day or less), or 5 g-mil/100 in²/day or less (i.e., 2.0g-mm/m²·day or less), or 3 g-mil/100 in²/day or less (i.e., 1.2g-mm/m²·day or less), or 2 g-mil/100 in²/day or less (i.e., 0.8g-mm/m²·day or less), or 1 g-mil/100 in²/day or less (i.e., 0.4g-mm/m²·day or less), or less than 1 g-mil/100 in²/day (i.e., less than0.4 g-mm/m²·day). As used herein, moisture vapor transmission rate(“MVTR”) is given in g-mil/100 in²/day, and is measured at 20° C. andaccording to ASTM F1249-99. In a preferred aspect of this embodiment,the relatively soft HNP composition comprises a low modulus HNP preparedusing a cation source which is less hydrophilic than conventionalmagnesium-based cation sources. Suitable moisture resistant HNPcompositions are disclosed, for example, in copending U.S. patentapplication Ser. No. 11/270,066 and U.S. Patent Application PublicationNo. 2005/0267240, the entire disclosures of which are herebyincorporated herein by reference.

Relatively soft HNP compositions of the present invention are notlimited by any particular method or any particular equipment for makingthe compositions. In a preferred embodiment, the composition is preparedby the following process. The acid polymer(s), preferably a VLMI-typeethylene-acid terpolymer, high molecular weight organic acid(s) orsalt(s) thereof, and optionally additive(s)/filler(s) are simultaneouslyor individually fed into a melt extruder, such as a single or twin screwextruder. A suitable amount of cation source is simultaneously orsubsequently added such that at least 80%, preferably at least 90%, morepreferably at least 95%, and even more preferably 100%, of all acidgroups present are neutralized. The acid polymer may be at leastpartially neutralized prior to the above process. The components areintensively mixed prior to being extruded as a strand from the die-head.

Relatively soft HNP compositions of the present invention may be blendedwith one or more additional polymers, such as thermoplastic polymers andelastomers. Examples of thermoplastic polymers suitable for blendinginclude, but are not limited to, bimodal ionomers (e.g., as disclosed inU.S. Patent Application Publication No. 2004/0220343 and U.S. Pat. Nos.6,562,906 and 6,762,246, the entire disclosures of which are herebyincorporated herein by reference), ionomers modified with rosins (e.g.,as disclosed in U.S. Patent Application Publication No. 2005/0020741,the entire disclosure of which is hereby incorporated by reference),soft and resilient ethylene copolymers (e.g., as disclosed U.S. PatentApplication Publication No. 2003/0114565, the entire disclosure of whichis hereby incorporated herein by reference) polyolefins, polyamides,polyesters, polyethers, polycarbonates, polysulfones, polyacetals,polylactones, acryloritrile-butadiene-styrene resins, polyphenyleneoxide, polyphenylene sulfide, styrene-acrylonitrile resins, styrenemaleic anhydride, polyimides, aromatic polyketones, ionomers andionomeric precursors, acid copolymers, conventional HNPs, polyurethanes,grafted and non-grafted metallocene-catalyzed polymers, single-sitecatalyst polymerized polymers, high crystalline acid polymers, cationicionomers, and combinations thereof. Particular polyolefins suitable forblending include one or more, linear, branched, or cyclic, C₂-C₄₀olefins, particularly polymers comprising ethylene or propylenecopolymerized with one or more C₂-C₄₀ olefins, C₃-C₂₀ α-olefins, orC₃-C₁₀ α-olefins. Particular conventional HNPs suitable for blendinginclude, but are not limited to, one or more of the HNPs disclosed inU.S. Pat. Nos. 6,756,436, 6,894,098, and 6,953,820, the entiredisclosures of which are hereby incorporated herein by reference.Examples of elastomers suitable for blending with the invention polymersinclude natural and synthetic rubbers, including, but not limited to,ethylene propylene rubber (“EPR”), ethylene propylene diene rubber(“EPDM”), styrenic block copolymer rubbers (such as SI, SIS, SB, SBS,SIBS, and the like, where “S” is styrene, “I” is isobutylene, and “B” isbutadiene), butyl rubber, halobutyl rubber, copolymers of isobutyleneand para-alkylstyrene, halogenated copolymers of isobutylene andpara-alkylstyrene, natural rubber, polyisoprene, copolymers of butadienewith acrylonitrile, polychloroprene, alkyl acrylate rubber, chlorinatedisoprene rubber, acrylonitrile chlorinated isoprene rubber, andpolybutadiene rubber (cis and trans). Additional suitable blend polymersinclude those described in U.S. Pat. No. 5,981,658, for example atcolumn 14, lines 30 to 56, the entire disclosure of which is herebyincorporated herein by reference. The blends described herein may beproduced by post-reactor blending, by connecting reactors in series tomake reactor blends, or by using more than one catalyst in the samereactor to produce multiple species of polymer. The polymers may bemixed prior to being put into an extruder, or they may be mixed in anextruder.

Particularly suitable relatively soft HNP compositions include, but arenot limited to, the highly-resilient thermoplastic compositionsdisclosed in U.S. Patent Application Publication No. 2005/0148725; thehighly-neutralized ethylene copolymers disclosed in U.S. Pat. Nos.6,653,382 and 6,777,472, and U.S. Patent Application Publication No.2003/0130434; and the highly-resilient thermoplastic elastomercompositions disclosed in U.S. Pat. No. 6,815,480; the entiredisclosures of which are hereby incorporated herein by reference.

Relatively Hard HNP Composition

Relatively hard HNP compositions of the present invention have a Shore Dhardness of 45 or greater, and preferably have a Shore D hardness withthe range having a lower limit of 45 or 50 or 55 and an upper limit of75 or 80 Relatively hard HNP compositions of the present inventioncomprise at least one highly neutralized acid polymer. In a preferredembodiment, the highly neutralized acid polymer of the relatively hardHNP composition is a high modulus HNP having a modulus within the rangehaving a lower limit of 25,000 or 27,000 or 30,000 or 40,000 or 45,000or 50,000 or 55,000 or 60,000 psi and an upper limit of 72,000 or 75,000or 100,000 or 150,000 psi.

HNPs of the relatively hard HNP compositions of the present inventionare salts of acid copolymers. It is understood that the HNP may be ablend of two or more HNPs. Preferred acid copolymers are copolymers ofan α-olefin and a C₃-C₈ α,β-ethylenically unsaturated carboxylic acid.The acid is typically present in the acid copolymer in an amount withinthe range having a lower limit of 1 or 10 or 12 or 15 or 20 wt % and anupper limit of 25 or 30 or 35 or 40 wt %, based on the total weight ofthe acid copolymer. The α-olefin is preferably selected from ethyleneand propylene. The acid is preferably selected from (meth)acrylic acid,ethacrylic acid, maleic acid, crotonic acid, fumaric acid, and itaconicacid. (meth)acrylic acid is particularly preferred. In a preferredembodiment, the HNP of the relatively hard HNP composition has a higherlevel of acid than the HNP of the relatively soft HNP composition.

Suitable acid copolymers include partially neutralized acid polymers.Examples of suitable partially neutralized acid polymers include, butare not limited to, Surlyn® ionomers, commercially available from E. I.du Pont de Nemours and Company; Aclyn® ionomers, commercially availablefrom Honeywell International Inc.; and lotek® ionomers, commerciallyavailable from ExxonMobil Chemical Company. Also suitable are DuPont®HPF 1000 and DuPont® HPF 2000, ionomeric materials commerciallyavailable from E. I. du Pont de Nemours and Company. Additional suitableacid polymers are more fully described, for example, in U.S. Pat. Nos.6,562,906, 6,762,246, and 6,953,820 and U.S. Patent ApplicationPublication Nos. 2005/0049367, 2005/0020741, and 2004/0220343, theentire disclosures of which are hereby incorporated herein by reference.

In a preferred embodiment, the HNP of the relatively hard HNPcomposition is formed by reacting an acid copolymer with a sufficientamount of cation source such that at least 80%, preferably at least 90%,more preferably at least 95%, and even more preferably 100%, of all acidgroups present are neutralized. Suitable cation sources include metalions and compounds of alkali metals, alkaline earth metals, andtransition metals; metal ions and compounds of rare earth elements;silicone, silane, and silicate derivatives and complex ligands; andcombinations thereof. Preferred cation sources are metal ions andcompounds of magnesium, sodium, potassium, cesium, calcium, barium,manganese, copper, zinc, tin, lithium, and rare earth metals. Metal ionsand compounds of calcium and magnesium are particularly preferred. Theacid copolymer may be at least partially neutralized prior to contactingthe acid copolymer with the cation source to form the HNP. As previouslystated, methods of preparing ionomers, and the acid copolymers on whichionomers are based, are disclosed, for example, in U.S. Pat. Nos.3,264,272, and 4,351,931, and U.S. Patent Application Publication No.2002/0013413.

Relatively hard HNP compositions of the present invention optionallycontain one or more melt flow modifiers. The amount of melt flowmodifier in the composition is readily determined such that the meltflow index of the composition is at least 0.1 g/10 min preferably from0.5 g/10 min to 10.0 g/10 min, and more preferably from 1.0 g/10 min to6.0 g/10 min, as measured using ASTM D-1238, condition E, at 190° C.,using a 2160 gram weight.

Suitable melt flow modifiers include, but are not limited to, highmolecular weight organic acids and salts thereof, polyamides,polyesters, polyacrylates, polyurethanes, polyethers, polyureas,polyhydric alcohols, and combinations thereof. Suitable organic acidsare aliphatic organic acids, aromatic organic acids, saturatedmono-functional organic acids, unsaturated monofunctional organic acids,multi-unsaturated mono-functional organic acids, and dimerizedderivatives thereof. Particular examples of suitable organic acidsinclude, but are not limited to, caproic acid, caprylic acid, capricacid, lauric acid, stearic acid, behenic acid, erucic acid, oleic acid,linoleic acid, myristic acid, benzoic acid, palmitic acid, phenylaceticacid, naphthalenoic acid, dimerized derivatives thereof. Suitableorganic acids are more fully described, for example, in U.S. Pat. No.6,756,436, the entire disclosure of which is hereby incorporated hereinby reference.

Additional melt flow modifiers suitable for use in compositions of thepresent invention, include the non-fatty acid melt flow modifiersdescribed in copending U.S. patent application Ser. Nos. 11/216,725 and11/216,726, the entire disclosures of which are hereby incorporatedherein by reference.

Relatively hard HNP compositions of the present invention optionallyinclude additive(s) and/or filler(s) in an amount within the rangehaving a lower limit of 0 or 5 or 10 wt %, and an upper limit of 25 or30 or 50 wt %, based on the total weight of the relatively hard HNPcomposition. Suitable additives and fillers include those previouslydescribed as suitable for the relatively soft HNP compositions of thepresent invention.

Relatively hard HNP compositions of the present invention optionallycontain a low modulus HNP.

In a particular embodiment, the relatively hard HNP composition has anMVTR of 8 g-mil/100 in²/day or less (i.e., 3.2 g-mm/m²·day or less), or5 g-mil/100 in²/day or less (i.e., 2.0 g-mm/m²·day or less), or 3g-mil/100 in²/day or less (i.e., 1.2 g-mm/m²·day or less), or 2g-mil/100 in²/day or less (i.e., 0.8 g-mm/m²·day or less), or 1g-mil/100 in²/day or less (i.e., 0.4 g-mm/m²·day or less), or less than1 g-mil/100 in²/day (i.e., less than 0.4 g-mm/m²·day). In a preferredaspect of this embodiment, the relatively hard HNP composition comprisesa high modulus HNP prepared using a cation source which is lesshydrophilic than conventional magnesium-based cation sources. Suitablemoisture resistant HNP compositions are disclosed, for example, incopending U.S. patent application Ser. No. 11/270,066 and U.S. PatentApplication Publication No. 2005/0267240, the entire disclosures ofwhich are hereby incorporated herein by reference.

Relatively hard HNP compositions of the present invention are notlimited by any particular method or any particular equipment for makingthe compositions. In a preferred embodiment, the composition is preparedby the following process. The acid polymer(s), preferably anethylene/(meth)acrylic acid copolymer, optional melt flow modifier(s),and optional additive(s)/filler(s) are simultaneously or individuallyfed into a melt extruder, such as a single or twin screw extruder. Asuitable amount of cation source is then added such that at least 80%,preferably at least 90%, more preferably at least 95%, and even morepreferably 100%, of all acid groups present are neutralized. The acidpolymer may be at least partially neutralized prior to the aboveprocess. The components are intensively mixed prior to being extruded asa strand from the die-head.

In another preferred embodiment, the relatively hard HNP composition isformed by combining a low modulus HNP with a sufficient amount of one ormore additional material(s), including, but not limited to, additives,fillers, and polymeric materials, to increase the modulus such that theresulting composition has a modulus as described above for the highmodulus HNP.

Relatively hard HNP compositions of the present invention may be blendedwith one or more additional polymers, such as thermoplastic polymers andelastomers. Examples of thermoplastic polymers and elastomers suitablefor blending include those previously described as suitable for blendingwith the relatively soft HNP compositions of the present invention.

Golf Ball Applications

Golf balls of the present invention comprise at least one layer formedfrom a relatively soft HNP composition and at least one layer formedfrom a relatively hard HNP composition.

Golf ball layers formed from HNP compositions of the present inventionhave no substantial hardness difference between the center of the layerand the surface of the layer. This lack of a hardness gradient is afurther attribute or characteristic property of such compositions. Thisdoes not necessarily mean that such a hardness gradient cannot becreated with such compositions, but that without some unusual oradditional step or process in the formation of the layer, a gradient ofless than 5 Shore D, and typically less than 3 Shore D, is created whenthe layer is molded using conventional injection or compression molding.There exists the potential for creating a hardness gradient with HNPcompositions, for example through the use of high energy radiationcuring, such as electron beam or gamma radiation, peroxide crosslinking,or other means of covalently crosslinking a surface; however, theexamples herein have substantially no hardness gradient.

In a preferred embodiment, the present invention provides a golf ballhaving a dual core and a cover, wherein the dual core includes a layerformed from a relatively soft HNP composition and a layer formed from arelatively hard HNP composition. The cover may be a single layer or dualcover.

Suitable cover layer materials for the golf balls disclosed hereininclude, but are not limited to, ionomer resin and blends thereof(particularly Surlyn® ionomer resin), polyurethanes, polyureas,(meth)acrylic acid, thermoplastic rubber polymers, polyethylene, andsynthetic or natural vulcanized rubber, such as balata. When used ascover layer materials, polyurethane and polyurea can be thermoset orthermoplastic. Thermoset materials can be formed into golf ball layersby conventional casting or reaction injection molding techniques.Thermoplastic materials can be formed into golf ball layers byconventional compression or injection molding techniques. Light stablepolyureas and polyurethanes are preferred for the outer cover layermaterial. Additional suitable cover and rubber core materials aredisclosed, for example, in U.S. Patent Application Publication No.2005/0164810, U.S. Pat. No. 5,919,100, and PCT Publications WO00/23519and WO00/29129, the entire disclosures of which are hereby incorporatedherein by reference. In embodiments of the present invention wherein agolf ball having a single layer cover is provided, the cover layermaterial is preferably selected from polyurethane and polyurea. Inembodiments of the present invention wherein a golf ball having a dualcover is provided, the inner cover layer is preferably a high modulusthermoplastic, and the outer cover layer is preferably selected frompolyurethane and polyurea.

The present invention is not limited by any particular process forforming the golf ball layer(s). It should be understood that thelayer(s) can be formed by any suitable technique, including injectionmolding, compression molding, casting, and reaction injection molding.

When injection molding is used, the HNP composition is typically in apelletized or granulated form that can be easily fed into the throat ofan injection molding machine wherein it is melted and conveyed via ascrew in a heated barrel at temperatures of from 150° F. to 600° F.,preferably from 200° F. to 500° F. The molten HNP composition isultimately injected into a closed mold cavity, which may be cooled, atambient or at an elevated temperature, but typically the mold is cooledto a temperature of from 50° F. to 70° F. After residing in the closedmold for a time of from 1 second to 300 seconds, preferably from 20seconds to 120 seconds, the core and/or core plus one or more additionalcore or cover layers is removed from the mold and either allowed to coolat ambient or reduced temperatures or is placed in a cooling fluid suchas water, ice water, dry ice in a solvent, or the like.

When compression molding is used to form a center, the HNP compositionis first formed into a preform or slug of material, typically in acylindrical or roughly spherical shape at a weight slightly greater thanthe desired weight of the molded core. Prior to this step, the HNPcomposition may be first extruded or otherwise melted and forced througha die after which it is cut into a cylindrical preform. It is thatpreform that is then placed into a compression mold cavity andcompressed at a mold temperature of from 150° F. to 400° F., preferablyfrom 250° F. to 350° F., and more preferably from 260° F. to 295° F.When compression molding a core or cover layer of an HNP composition, ahalf-shell is first formed via injection molding and then a corecomprising one or more layers is enclosed within two half shells andthen compression molded in a similar manner to the process previouslydescribed.

In the embodiments disclosed herein, the relatively soft HNP compositionand/or the relatively hard HNP composition, can be either foamed orfilled with density adjusting materials to provide desirable golf ballperformance characteristics.

Any of the dual core embodiments of the present invention may have thesame or different specific gravities. HNP compositions of the presentinvention, in the neat (i.e., unfilled) form, preferably have a specificgravity of from 0.95 g/cc to 0.99 g/cc. Any suitable filler, flake,fiber, particle, or the like, of an organic or inorganic material may beadded to the HNP composition to increase or decrease the specificgravity, particularly to adjust the weight distribution within the golfball, as further disclosed in U.S. Pat. Nos. 6,494,795, 6,547,677,6,743,123, 7,074,137, and 6,688,991, the entire disclosures of which arehereby incorporated herein by reference.

In a particular embodiment, the present invention provides a dual coregolf ball wherein the center (i.e., innermost core layer) has a specificgravity of 1.15 g/cc or less, preferably 1.10 g/cc or less, and morepreferably 1.00 g/cc or less, and wherein the outer core layer has aspecific gravity of 1.15 g/cc or greater, preferably 1.5 g/cc orgreater, and more preferably 2.0 g/cc or greater.

In another particular embodiment, the present invention provides a dualcore golf ball wherein the center has a specific gravity of 1.15 g/cc orgreater, preferably 1.5 g/cc or greater, and more preferably 2.0 g/cc orgreater, and wherein the outer core layer has a specific gravity of 1.15g/cc or less, preferably 1.10 g/cc or less, and more preferably 1.00g/cc or less.

In another embodiment, the present invention provides a golf ballcomprising a center, at least one additional core layer, at least onecover layer, and an optional intermediate layer disposed between thecore and the cover, wherein the center and additional core layer eachhave a reduced specific gravity (i.e., lower than that of the neat HNPcomposition), a cover layer and/or an intermediate layer have anincreased specific gravity (i.e., greater than that of the neat HNPcomposition), and the resulting golf ball has a weight of 46.0 ounces orless.

In yet another embodiment, the present invention provides a golf ballcomprising a center, at least one additional core layer, at least onecover layer, and an optional intermediate layer disposed between thecore and the cover, wherein the center and additional core layer eachhave an increased specific gravity (i.e., greater than that of the neatHNP composition), a cover layer and/or an intermediate layer have areduced specific gravity (i.e., lower than that of the neat HNPcomposition), and the resulting golf ball has a weight of 46.0 ounces orless.

Golf ball cores of the present invention, including dual cores andmulti-layered cores, typically have a compression of less than 100, andpreferably have a compression within the range having a lower limit of20 or 50 and an upper limit of 80 or 90 or 100. Golf ball cores of thepresent invention typically have a coefficient of restitution (“COR”) at125 ft/s of at least 0.75, preferably at least 0.78, and more preferablyat least 0.79.

Golf balls of the present invention typically have a compression of lessthan 120, and preferably have a compression within the range having alower limit of 60 or 75 and an upper limit of 105 or 110 or 120. Golfballs of the present invention typically have a COR at 125 ft/s of atleast 0.75, preferably at least 0.78, and more preferably at least 0.79.

For purposes of the present invention, compression is measured accordingto a known procedure, using an Atti compression test device, wherein apiston is used to compress a ball against a spring. The travel of thepiston is fixed and the deflection of the spring is measured. Themeasurement of the deflection of the spring does not begin with itscontact with the ball; rather, there is an offset of approximately thefirst 1.25 mm (0.05 inches) of the spring's deflection. Very lowstiffness cores will not cause the spring to deflect by more than 1.25mm and therefore have a zero compression measurement. The Atticompression tester is designed to measure objects having a diameter of42.7 mm (1.68 inches); thus, smaller objects, such as golf ball cores,must be shimmed to a total height of 42.7 mm to obtain an accuratereading.

For purposes of the present invention, COR is determined according to aknown procedure wherein a golf ball or golf ball subassembly (e.g., agolf ball core) is fired from an air cannon at a given velocity (125ft/s for purposes of the present invention). Ballistic light screens arelocated between the air cannon and the steel plate to measure ballvelocity. As the ball travels toward the steel plate, it activates eachlight screen, and the time at each light screen is measured. Thisprovides an incoming transmit time period inversely proportional to theball's incoming velocity. The ball impacts the steel plate and reboundsthough the light screens, which again measure the time period requiredto transmit between the light screens. This provides an outgoingtransmit time period inversely proportional to the ball's outgoingvelocity. COR is then calculated as the ratio of the incoming transmittime period to the outgoing transmit time period, COR=T_(in)/T_(out).

Dual Core/Single Cover Golf Balls

In one embodiment, the present invention provides a golf ball comprisingan inner core layer formed from a relatively soft HNP composition, anouter core layer formed from a relatively hard HNP composition, and acover having a single layer. In a particular aspect of this embodiment,the relatively soft HNP composition has a Shore D hardness of 55 orless, preferably from 10 to 55, the relatively hard HNP composition hasa Shore D hardness of 45 or greater, preferably from 45 to 80, and theShore D hardness of the relatively soft HNP composition is less than theShore D hardness of the relatively hard HNP composition. In anotherparticular aspect of this embodiment, the HNP of the inner core layercomposition is a low modulus HNP having a modulus within the rangehaving a lower limit of 1,000 or 5,000 or 10,000 psi and an upper limitof 17,000 or 28,000 or 30,000 or 50,000 psi and the HNP of the outercore layer composition is a high modulus HNP having a modulus within therange having a lower limit of 25,000 or 27,000 or 45,000 or 55,000 or60,000 psi and an upper limit of 72,000 or 75,000 or 100,000 or 150,000psi. In another particular aspect of this embodiment, the inner corelayer has a diameter within the range having a lower limit of 0.500 or0.750 or 1.000 inches and an upper limit of 1.550 or 1.570 or 1.580inches; the outer core has a thickness within the range having a lowerlimit of 0.020 or 0.025 or 0.032 inches and an upper limit of 0.310 or0.440 or 0.560 inches; and the cover has a thickness within the rangehaving a lower limit of 0.020 or 0.025 or 0.030 inches and an upperlimit of 0.065 or 0.080 or 0.090 inches. In yet another particularaspect of this embodiment, the inner core layer has a compression of 80or less, or 70 or less, or 65 or less.

In another embodiment, the present invention provides a golf ballcomprising an inner core layer formed from a relatively hard HNPcomposition, an outer core layer formed from a relatively soft HNPcomposition, and a cover having a single layer. In a particular aspectof this embodiment, the relatively soft HNP composition has a Shore Dhardness of 55 or less, preferably from 10 to 55, the relatively hardHNP composition has a Shore D hardness of 45 or greater, preferably from45 to 80, and the Shore D hardness of the relatively soft HNPcomposition is less than the Shore D hardness of the relatively hard HNPcomposition. In another particular aspect of this embodiment, the HNP ofthe inner core layer composition is a high modulus HNP having a moduluswithin the range having a lower limit of 25,000 or 27,000 or 45,000 or55,000 or 60,000 psi and an upper limit of 72,000 or 75,000 or 100,000or 150,000 psi and the HNP of the outer core layer composition is a lowmodulus HNP having a modulus within the range having a lower limit of1,000 or 5,000 or 10,000 psi and an upper limit of 17,000 or 28,000 or30,000 or 50,000 psi. In another particular aspect of this embodiment,the inner core layer has a diameter within the range having a lowerlimit of 0.500 or 0.750 or 1.000 inches and an upper limit of 1.550 or1.570 or 1.580 inches; the outer core has a thickness within the rangehaving a lower limit of 0.020 or 0.025 or 0.032 inches and an upperlimit of 0.310 or 0.440 or 0.560 inches; and the cover has a thicknesswithin the range having a lower limit of 0.020 or 0.025 or 0.030 inchesand an upper limit of 0.065 or 0.080 or 0.090 inches. In yet anotherparticular aspect of this embodiment, the inner core layer has acompression of at least 80, and preferably has a compression within therange having a lower limit of 80 or 90 or 100 and an upper limit of 130or 140.

Dual Core/Dual Cover Golf Balls

In another embodiment, the present invention provides a golf ballcomprising an inner core layer formed from a relatively soft HNPcomposition, an outer core layer formed from a relatively hard HNPcomposition, and a dual cover. In a particular aspect of thisembodiment, the relatively soft HNP composition has a Shore D hardnessof 55 or less, preferably from 10 to 55, the relatively hard HNPcomposition has a Shore D hardness of 45 or greater, preferably from 45to 80, and the Shore D hardness of the relatively soft HNP compositionis less than the Shore D hardness of the relatively hard HNPcomposition. In another particular aspect of this embodiment, the HNP ofthe inner core layer composition is a low modulus HNP having a moduluswithin the range having a lower limit of 1,000 or 5,000 or 10,000 psiand an upper limit of 17,000 or 28,000 or 30,000 or 50,000 psi and theHNP of the outer core layer composition is a high modulus HNP having amodulus within the range having a lower limit of 25,000 or 27,000 or45,000 or 55,000 or 60,000 psi and an upper limit of 72,000 or 75,000 or100,000 or 150,000 psi. In another particular aspect of this embodiment,the inner core layer has a diameter within the range having a lowerlimit of 0.500 or 0.750 or 1.000 inches and an upper limit of 1.550 or1.570 or 1.580 inches; the outer core has a thickness within the rangehaving a lower limit of 0.020 or 0.025 or 0.032 inches and an upperlimit of 0.310 or 0.440 or 0.560 inches; and the dual cover has anoverall thickness within the range having a lower limit of 0.020 or0.025 or 0.060 inches and an upper limit of 0.075 or 0.090 or 0.110inches. In yet another particular aspect of this embodiment, the innercore layer has a compression of 80 or less, or 70 or less, or 65 orless.

In another embodiment, the present invention provides a golf ballcomprising an inner core layer formed from a relatively hard HNPcomposition, an outer core layer formed from a relatively soft HNPcomposition, and a dual cover. In a particular aspect of thisembodiment, the relatively soft HNP composition has a Shore D hardnessof 55 or less, preferably from 10 to 55, the relatively hard HNPcomposition has a Shore D hardness of 45 or greater, preferably from 45to 80, and the Shore D hardness of the relatively soft HNP compositionis less than the Shore D hardness of the relatively hard HNPcomposition. In another particular aspect of this embodiment, the HNP ofthe inner core layer composition is a high modulus HNP having a moduluswithin the range having a lower limit of 25,000 or 27,000 or 45,000 or55,000 or 60,000 psi and an upper limit of 72,000 or 75,000 or 100,000or 150,000 psi and the HNP of the outer core layer composition is a lowmodulus HNP having a modulus within the range having a lower limit of1,000 or 5,000 or 10,000 psi and an upper limit of 17,000 or 28,000 or30,000 or 50,000 psi. In another particular aspect of this embodiment,the inner core layer has a diameter within the range having a lowerlimit of 0.500 or 0.750 or 1000 inches and an upper limit of 1.550 or1.570 or 1.580 inches; the outer core has a thickness within the rangehaving a lower limit of 0.020 or 0.025 or 0.032 inches and an upperlimit of 0.310 or 0.440 or 0.560 inches; and the dual cover has anoverall thickness within the range having a lower limit of 0.020 or0.025 or 0.060 inches and an upper limit of 0.075 or 0.090 or 0.110inches. In yet another particular aspect of this embodiment, the innercore layer has a compression of at least 80, and preferably has acompression within the range having a lower limit of 80 or 90 or 100 andan upper limit of 130 or 140.

Golf Balls Having Multi-Layered Cores

By the present invention, it has been found that, in some embodiments,the use of a relatively soft HNP-based layer and a relatively hardHNP-based layer eliminates the need for conventional rubber-basedlayers. However, it is contemplated that it may be desirable to includeconventional rubber-based layers in some embodiments of the presentinvention.

Thus, in one embodiment, the present invention provides a golf ballcomprising:

-   -   (a) an inner core layer comprising a rubber composition,    -   (b) an intermediate core layer formed from a relatively soft HNP        composition,    -   (c) an outer core layer formed from a relatively hard HNP        composition, and    -   (d) a cover having one or more layers.

In a particular aspect of this embodiment, the relatively soft HNPcomposition has a Shore D hardness of 55 or less, preferably from 10 to55, the relatively hard HNP composition has a Shore D hardness of 45 orgreater, preferably from 45 to 80, and the Shore D hardness of therelatively soft HNP composition is less than the Shore D hardness of therelatively hard HNP composition. In another particular aspect of thisembodiment, the HNP of the intermediate core layer composition is a lowmodulus HNP having a modulus within the range having a lower limit of1,000 or 5,000 or 10,000 psi and an upper limit of 17,000 or 28,000 or30,000 or 50,000 psi and the HNP of the outer core layer composition isa high modulus HNP having a modulus within the range having a lowerlimit of 25,000 or 27,000 or 45,000 or 55,000 or 60,000 psi and an upperlimit of 72,000 or 75,000 or 100,000 or 150,000 psi. In anotherparticular aspect of this embodiment, the inner core layer has adiameter within the range having a lower limit of 0.500 or 0.750 or1.000 inches and an upper limit of 1.550 or 1.570 or 1.580 inches; theintermediate core layer has a thickness within the range having a lowerlimit of 0.020 or 0.025 or 0.032 inches and an upper limit of 0.150 or0.220 or 0.280 inches; the outer core has a thickness within the rangehaving a lower limit of 0.020 or 0.025 or 0.032 inches and an upperlimit of 0.310 or 0.440 or 0.560 inches; and the cover has an overallthickness within the range having a lower limit of 0.020 or 0.025 or0.030 inches and an upper limit of 0.065 or 0.080 or 0.090 inches. Inyet another particular aspect of this embodiment, the inner core layerhas a compression of 80 or less, or 70 or less, or 65 or less.

In another embodiment, the present invention provides a golf ballcomprising:

-   -   (a) an inner core layer formed from a relatively soft HNP        composition,    -   (b) an intermediate core layer comprising a rubber composition,    -   (c) an outer core layer formed from a relatively hard HNP        composition, and    -   (d) a cover having one or more layers.

In a particular aspect of this embodiment, the relatively soft HNPcomposition has a Shore D hardness of 55 or less, preferably from 10 to55, the relatively hard HNP composition has a Shore D hardness of 45 orgreater, preferably from 45 to 80, and the Shore D hardness of therelatively soft FNP composition is less than the Shore D hardness of therelatively hard HNP composition. In another particular aspect of thisembodiment, the HNP of the inner core layer composition is a low modulusHNP having a modulus within the range having a lower limit of 1,000 or5,000 or 10,000 psi and an upper limit of 17,000 or 28,000 or 30,000 or50,000 psi and the HNP of the outer core layer composition is a highmodulus HNP having a modulus within the range having a lower limit of25,000 or 27,000 or 45,000 or 55,000 or 60,000 psi and an upper limit of72,000 or 75,000 or 100,000 or 150,000 psi. In another particular aspectof this embodiment, the inner core layer has a diameter within the rangehaving a lower limit of 0.500 or 0.750 or 1.000 inches and an upperlimit of 1.550 or 1.570 or 1.580 inches; the intermediate core layer hasa thickness within the range having a lower limit of 0.020 or 0.025 or0.032 inches and an upper limit of 0.150 or 0.220 or 0.280 inches; theouter core has a thickness within the range having a lower limit of0.020 or 0.025 or 0.032 inches and an upper limit of 0.310 or 0.440 or0.560 inches; and the cover has an overall thickness within the rangehaving a lower limit of 0.020 or 0.025 or 0.030 inches and an upperlimit of 0.065 or 0.080 or 0.090 inches. In yet another particularaspect of this embodiment, the inner core layer has a compression of 80or less, or 70 or less, or 65 or less.

In another embodiment, the present invention provides a golf ballcomprising:

-   -   (a) an inner core layer formed from a relatively soft HNP        composition,    -   (b) an intermediate core layer formed from a relatively hard HNP        composition,    -   (c) an outer core layer comprising a rubber composition, and    -   (d) a cover having one or more layers.

In a particular aspect of this embodiment, the relatively soft HNPcomposition has a Shore D hardness of 55 or less, preferably from 10 to55, the relatively hard HNP composition has a Shore D hardness of 45 orgreater, preferably from 45 to 80, and the Shore D hardness of is therelatively soft HNP composition is less than the Shore D hardness of therelatively hard HNP composition. In another particular aspect of thisembodiment, the HNP of the inner core layer composition is a low modulusHNP having a modulus within the range having a lower limit of 1,000 or5,000 or 10,000 psi and an upper limit of 17,000 or 28,000 or 30,000 or50,000 psi and the HNP of the intermediate core layer composition is ahigh modulus HNP having a modulus within the range having a lower limitof 25,000 or 27,000 or 45,000 or 55,000 or 60,000 psi and an upper limitof 72,000 or 75,000 or 100,000 or 150,000 psi. In another particularaspect of this embodiment, the inner core layer has a diameter withinthe range having a lower limit of 0.500 or 0.750 or 1.000 inches and anupper limit of 1.550 or 1.570 or 1.580 inches; the intermediate corelayer has a thickness within the range having a lower limit of 0.020 or0.025 or 0.032 inches and an upper limit of 0.150 or 0.220 or 0.280inches; the outer core has a thickness within the range having a lowerlimit of 0.020 or 0.025 or 0.032 inches and an upper limit of 0.310 or0.440 or 0.560 inches; and the cover has an overall thickness within therange having a lower limit of 0.020 or 0.025 or 0.030 inches and anupper limit of 0.065 or 0.080 or 0.090 inches. In yet another particularaspect of this embodiment, the inner core layer has a compression of 80or less, or 70 or less, or 65 or less.

In another embodiment, the present invention provides a golf ballcomprising:

-   -   (a) an inner core layer comprising a rubber composition,    -   (b) an intermediate core layer formed from a relatively hard HNP        composition,    -   (c) an outer core layer formed from a relatively soft HNP        composition, and    -   (d) a cover having one or more layers.

In a particular aspect of this embodiment, the relatively soft HNPcomposition has a Shore D hardness of 55 or less, preferably from 10 to55, the relatively hard HNP composition has a Shore D hardness of 45 orgreater, preferably from 45 to 80, and the Shore D hardness of therelatively soft HNP composition is less than the Shore D hardness of therelatively hard HNP composition. In another particular aspect of thisembodiment, the HNP of the outer core layer composition is a low modulusHNP having a modulus within the range having a lower limit of 1,000 or5,000 or 10,000 psi and an upper limit of 17,000 or 28,000 or 30,000 or50,000 psi and the HNP of the intermediate core layer composition is ahigh modulus HNP having a modulus within the range having a lower limitof 25,000 or 27,000 or 45,000 or 55,000 or 60,000 psi and an upper limitof 72,000 or 75,000 or 100,000 or 150,000 psi. In another particularaspect of this embodiment, the inner core layer has a diameter withinthe range having a lower limit of 0.500 or 0.750 or 1.000 inches and anupper limit of 1.550 or 1.570 or 1.580 inches; the intermediate corelayer has a thickness within the range having a lower limit of 0.020 or0.025 or 0.032 inches and an upper limit of 0.150 or 0.220 or 0.280inches; the outer core has a thickness within the range having a lowerlimit of 0.020 or 0.025 or 0.032 inches and an upper limit of 0.310 or0.440 or 0.560 inches; and the cover has an overall thickness within therange having a lower limit of 0.020 or 0.025 or 0.030 inches and anupper limit of 0.065 or 0.080 or 0.090 inches. In yet another particularaspect of this embodiment, the inner core layer has a compression of 80or less, or 70 or less, or 65 or less.

In another embodiment, the present invention provides a golf ballcomprising:

-   -   (a) an inner core layer formed from a relatively hard HNP        composition,    -   (b) an intermediate core layer formed from a relatively soft HNP        composition,    -   (c) an outer core layer comprising a rubber composition, and    -   (d) a cover having one or more layers.

In a particular aspect of this embodiment, the relatively soft HNPcomposition has a Shore D hardness of 55 or less, preferably from 10 to55, the relatively hard HNP composition has a Shore D hardness of 45 orgreater, preferably from 45 to 80, and the Shore D hardness of therelatively soft HNP composition is less than the Shore D hardness of therelatively hard HNP composition. In another particular aspect of thisembodiment, the HNP of the intermediate core layer composition is a lowmodulus HNP having a modulus within the range having a lower limit of1,000 or 5,000 or 10,000 psi and an upper limit of 17,000 or 28,000 or30,000 or 50,000 psi and the HNP of the inner core layer composition isa high modulus HNP having a modulus within the range having a lowerlimit of 25,000 or 27,000 or 45,000 or 55,000 or 60,000 psi and an upperlimit of 72,000 or 75,000 or 100,000 or 150,000 psi. In anotherparticular aspect of this embodiment, the inner core layer has adiameter within the range having a lower limit of 0.500 or 0.750 or1.000 inches and an upper limit of 1.550 or 1.570 or 1.580 inches; theintermediate core layer has a thickness within the range having a lowerlimit of 0.020 or 0.025 or 0.032 inches and an upper limit of 0.150 or0.220 or 0.280 inches; the outer core has a thickness within the rangehaving a lower limit of 0.020 or 0.025 or 0.032 inches and an upperlimit of 0.310 or 0.440 or 0.560 inches; and the cover has an overallthickness within the range having a lower limit of 0.020 or 0.025 or0.030 inches and an upper limit of 0.065 or 0.080 or 0.090 inches. Inyet another particular aspect of this embodiment, the inner core layerhas a compression of at least 80, and preferably has a compressionwithin the range having a lower limit of 80 or 90 or 100 and an upperlimit of 130 or 140.

In another embodiment, the present invention provides a golf ballcomprising:

-   -   (a) an inner core layer formed from a relatively hard HNP        composition,    -   (b) an intermediate core layer comprising a rubber composition,    -   (c) an outer core layer formed from a relatively soft HNP        composition, and    -   (d) a cover having one or more layers.

In a particular aspect of this embodiment, the relatively soft HNPcomposition has a Shore D hardness of 55 or less, preferably from 10 to55, the relatively hard HNP composition has a Shore D hardness of 45 orgreater, preferably from 45 to 80, and the Shore D hardness of therelatively soft HNP composition is less than the Shore D hardness of therelatively hard HNP composition. In another particular aspect of thisembodiment, the HNP of the outer core layer composition is a low modulusHNP having a modulus within the range having a lower limit of 1,000 or5,000 or 10,000 psi and an upper limit of 17,000 or 28,000 or 30,000 or50,000 psi and the HNP of the inner core layer composition is a highmodulus HNP having a modulus within the range having a lower limit of25,000 or 27,000 or 45,000 or 55,000 or 60,000 psi and an upper limit of72,000 or 75,000 or 100,000 or 150,000 psi. In another particular aspectof this embodiment, the inner core layer has a diameter within the rangehaving a lower limit of 0.500 or 0.750 or 1.000 inches and an upperlimit of 1.550 or 1.570 or 1.580 inches; the intermediate core layer hasa thickness within the range having a lower limit of 0.020 or 0.025 or0.032 inches and an upper limit of 0.150 or 0.220 or 0.280 inches; theouter core has a thickness within the range having a lower limit of0.020 or 0.025 or 0.032 inches and an upper limit of 0.310 or 0.440 or0.560 inches; and the cover has an overall thickness within the rangehaving a lower limit of 0.020 or 0.025 or 0.030 inches and an upperlimit of 0.065 or 0.080 or 0.090 inches. In yet another particularaspect of this embodiment, the inner core layer has a compression of atleast 80, and preferably has a compression within the range having alower limit of 80 or 90 or 100 and an upper limit of 130 or 140.

Suitable rubbers for golf ball layers of the present invention includenatural and synthetic rubbers, including, but not limited to,polybutadiene, polyisoprene, ethylene propylene rubber (“EPR”), ethylenepropylene diene rubber (“EPDM”), styrenic block copolymer rubbers (suchas SI, SIS, SB, SBS, SIBS, and the like, where “S” is styrene, “I” isisobutylene, and “B” is butadiene), butyl rubber, halobutyl rubber,copolymers of isobutylene and para-alkylstyrene, halogenated copolymersof isobutylene and para-alkylstyrene, copolymers of butadiene withacrylonitrile, polychloroprene, alkyl acrylate rubber, chlorinatedisoprene rubber, acrylonitrile chlorinated isoprene rubber, andcombinations thereof. Diene rubbers are preferred.

In embodiments wherein the inner core layer comprises a rubbercomposition, the inner core layer is preferably formed from a reactionproduct of a rubber, a crosslinking agent, a filler, a co-crosslinkingagent or free radical initiator, and optionally a cis-to-trans catalyst.The rubber is preferably selected from polybutadiene andstyrene-butadiene. The crosslinking agent typically includes a metalsalt, such as a zinc salt or magnesium salt, of an acid having from 3 to8 carbon atoms, such as (meth)acrylic acid. The free radical initiatorcan be any known polymerization initiator which decomposes during thecure cycle, including, but not limited to, dicumyl peroxide,1,1-di-(t-butylperoxy) 3,3,5-trimethyl cyclohexane, a-abis-(t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5di-(t-butylperoxy)hexane or di-t-butyl peroxide, and mixtures thereof.Suitable types and amounts of rubber, crosslinking agent, filler,co-crosslinking agent, and initiator are more fully described in, forexample, U.S. Patent Application Publication No. 2003/0144087, theentire disclosure of which is hereby incorporated herein by reference.Reference is also made to U.S. Patent Application Publication No.2003/0144087 for various ball constructions and materials that can beused in golf ball core, intermediate, and cover layers.

Wound Golf Balls

In one embodiment, the present invention provides a wound golf ballcomprising a core, a conventional clastomeric winding wound around thecore, and a cover made from a conventional golf ball cover material,e.g., ionomer resin and blends thereof (particularly Surlyn® ionomerresin), thermoset polyurethanes and polyureas, thermoplasticpolyurethanes and polyureas, (meth)acrylic acid, thermoplastic rubberpolymers, polyethylene, and synthetic or natural vulcanized rubber, suchas balata.

In a particular aspect of this embodiment, the core includes an innercore layer formed from a relatively soft HNP composition and an outercore layer formed from a relatively hard HNP composition. The relativelysoft HNP composition has a Shore D hardness of 55 or less, preferablyfrom 10 to 55, the relatively hard HNP composition has a Shore Dhardness of 45 or greater, preferably from 45 to 80, and the Shore Dhardness of the relatively soft HNP composition is less than the Shore Dhardness of the relatively hard HNP composition. The inner core layerpreferably has a diameter of from 0.500 to 1.250 inches. The outer corelayer preferably has a thickness of from 0.125 to 0.525 inches. Theoverall core diameter is preferably from 1.000 to 1.550 inches. The HNPof the inner core layer composition is preferably a low modulus HNPhaving a modulus within the range having a lower limit of 1,000 or 5,000or 10,000 psi and an upper limit of 17,000 or 28,000 or 30,000 or 50,000psi. The HNP of the outer cover layer composition is preferably a highmodulus HNP having a modulus within the range having a lower limit of25,000 or 27,000 or 45,000 or 55,000 or 60,000 psi and an upper limit of72,000 or 75,000 or 100,000 or 150,000 psi.

In another particular aspect of this embodiment, the core includes aninner core layer formed from a relatively hard HNP composition and anouter core layer formed from a relatively soft HNP composition. Therelatively soft HNP composition has a Shore D hardness of 55 or less,preferably from 10 to 55, the relatively hard HNP composition has aShore D hardness of 45 or greater, preferably from 45 to 80, and theShore D hardness of the relatively soft HNP composition is less than theShore D hardness of the relatively hard HNP composition. The inner corelayer preferably has a diameter of from 0.500 to 1.250 inches. The outercore layer preferably has a thickness of from 0.125 to 0.525 inches. Theoverall core diameter is preferably from 1.000 to 1.550 inches. The HNPof the inner cover layer composition is preferably a high modulus HNPhaving a modulus within the range having a lower limit of 25,000 or27,000 or 45,000 or 55,000 or 60,000 psi and an upper limit of 72,000 or75,000 or 100,000 or 150,000 psi. The HNP of the outer core layercomposition is preferably a low modulus HNP having a modulus within therange having a lower limit of 1,000 or 5,000 or 10,000 psi and an upperlimit of 17,000 or 28,000 or 30,000 or 50,000 psi.

Wound golf balls of the present invention are manufactured by well knowntechniques, such as those disclosed, for example, in U.S. Pat. No.4,846,910.

Additional Examples of Suitable HNPs

The HNPs of Table 1 below are ethylene/acrylic acid copolymers andterpolymers that have been found to be particularly useful as therelatively soft HNP and/or the relatively hard HNP of the presentinvention. TABLE 1 Cation Flexural Hardness² Acrylic Acid Fatty FattyAcid Cation Content Modulus¹ (Shore C, Hardness² Polymer Content AcidContent Example Source (wt %) (psi) 18 day) (Shore D) Type³ (wt %) Type(wt %) 1 Ca/Mg 3.25/0.70 71,600 88 57 copolymer 14.9 stearic * 2 Ca/Li2.94/0.36 70,300 89 58 copolymer 13.2 stearic * 3 Ca 4.05 70,100 92 60copolymer 13.5 stearic * 4 Ca/Zn 2.52/2.31 60,400 88 58 copolymer 13.5stearic * 5 Mg 2.55 38,300 84 52 terpolymer 10.0 stearic 33 6 Mg 2.8627,600 84 52 copolymer 12.8 oleic 24 7 Mg 2.67 16,300 78 45 terpolymer11.5 oleic 27 8 Mg 3.21 10,600 70 40 terpolymer 12.7 oleic 33 9 Mg 2.8810,400 69 39 terpolymer 11.8 oleic 31 10 Ca 3.21 60,300 * 37 copolymer10.2 stearic * 11 Ca 3.62 69,300 90 60 copolymer 11.9 stearic * 12 Mg2.24 7,300 * 37 terpolymer 12.3 erucic *¹Flexural modulus was measured according to ASTM D790-03 Procedure B.²Hardness was measured according to ASTM D2240.³copolymer: poly(ethylene-acrylic acid) terpolymer:poly(ethylene-n-butyl acrylate-acrylic acid)* Data not available.

In embodiments of the present invention directed to a golf ball havingan inner core, intermediate core, or outer core layer formed from arelatively soft HNP composition, Examples 5-10 and 12 are particularlysuitable for use as the relatively soft HNP composition.

In embodiments of the present invention directed to a golf ball havingan inner core layer or intermediate core layer formed from a relativelyhard HNP composition, Examples 1-6 and 11 are particularly suitable foruse as the relatively hard HNP composition of the inner core layer orintermediate core layer.

In embodiments of the present invention directed to a golf ball havingan outer core layer formed from a relatively hard HNP composition,Examples 1-4 and 11 are particularly suitable for use as the relativelyhard HNP composition of the outer core layer.

When numerical lower limits and numerical upper limits are set forthherein, it is contemplated that any combination of these values may beused.

All patents, publications, test procedures, and other references citedherein, including priority documents, are fully incorporated byreference to the extent such disclosure is not inconsistent with thisinvention and for all jurisdictions in which such incorporation ispermitted.

While the illustrative embodiments of the invention have been describedwith particularity, it will be understood that various othermodifications will be apparent to and can be readily made by those ofordinary skill in the art without departing from the spirit and scope ofthe invention. Accordingly, it is not intended that the scope of theclaims appended hereto be limited to the examples and descriptions setforth herein, but rather that the claims be construed as encompassingall of the features of patentable novelty which reside in the presentinvention, including all features which would be treated as equivalentsthereof by those of ordinary skill in the art to which the inventionpertains.

1. A golf ball comprising: (a) an inner core layer formed from a first HNP composition, the first HNP composition having a Shore D hardness of 55 or less and comprising a highly neutralized ethylene/(meth)acrylic acid/alkyl(meth)acrylate copolymer; (b) an outer core layer formed from a second HNP composition, the second HNP composition having a Shore D hardness of 45 or greater and comprising a highly neutralized ethylene/(meth)acrylic acid copolymer; and (c) a cover; wherein the Shore D hardness of the first HNP composition is less than the Shore D hardness of the second HNP composition.
 2. The golf ball of claim 1, wherein the Shore D hardness of the first HNP composition is from 10 to
 55. 3. The golf ball of claim 1, wherein the Shore D hardness of the first HNP composition is from 20 to
 50. 4. The golf ball of claim 1, wherein the Shore D hardness of the first HNP composition is from 30 to
 48. 5. The golf ball of claim 1, wherein the Shore D hardness of the second HNP composition is from 50 to
 80. 6. The golf ball of claim 1, wherein the Shore D hardness of the second HNP composition is from 55 to
 75. 7. The golf ball of claim 1, wherein the Shore D hardness of the first HNP composition is at least 3 less than the Shore D hardness of the second HNP composition.
 8. The golf ball of claim 1, wherein the first HNP composition has a modulus of from 1,000 psi to 50,000 psi.
 9. The golf ball of claim 1, wherein the second HNP composition has a modulus of from 25,000 psi to 150,000 psi.
 10. The golf ball of claim 1, wherein the first HNP composition has a modulus of from 1,000 psi to 50,000 psi, the second HNP composition has a modulus of from 25,000 psi to 150,000 psi, and the modulus of the first HNP composition is at least 10% less than the modulus of the second HNP composition.
 11. The golf ball of claim 10, wherein the modulus of the first HNP composition is at least 25% less than the modulus of the second HNP composition.
 12. The golf ball of claim 1, wherein the golf ball additionally comprises an intermediate core layer disposed between the inner core layer and the outer core layer, wherein the intermediate core layer is formed from a diene rubber composition.
 13. A golf ball comprising: (a) an inner core layer formed from a first HNP composition, the first HNP composition having a Shore D hardness of 45 or greater and comprising a highly neutralized ethylene/(meth)acrylic acid copolymer; (b) an outer core layer formed from a second HNP composition, the second HNP composition having a Shore D hardness of 55 or less and comprising a highly neutralized ethylene/(meth)acrylic acid/alkyl(meth)acrylate copolymer; and (c) a cover; wherein the Shore D hardness of the first HNP composition is greater than the Shore D hardness of the second HNP composition.
 14. The golf ball of claim 13, wherein the Shore D hardness of the second HNP composition is from 10 to
 55. 15. The golf ball of claim 13, wherein the Shore D hardness of the second HNP composition is from 20 to
 50. 16. The golf ball of claim 13, wherein the Shore D hardness of the first HNP composition is from 50 to
 80. 17. The golf ball of claim 13, wherein the Shore D hardness of the second HNP composition is at least 3 less than the Shore D hardness of the first HNP composition.
 18. The golf ball of claim 13, wherein the second HNP composition has a modulus of from 1,000 psi to 50,000 psi.
 19. The golf ball of claim 13, wherein the first HNP composition has a modulus of from 25,000 psi to 150,000 psi.
 20. The golf ball of claim 13, wherein the second HNP composition has a modulus of from 1,000 psi to 50,000 psi, the first HNP composition has a modulus of from 25,000 psi to 150,000 psi, and the modulus of the second HNP composition is at least 10% less than the modulus of the first HNP composition. 